Uppercase Words

<?php
$text = "Companies like
    HP, ORACLE and IBM target their platforms for cloud-based environment.
    IList<T> implements IEnumerable<T>. GoPHP is a 5P4PHP library.
";

$upperWords = preg_split("/[^A-Za-z]+/", $text, -1, PREG_SPLIT_NO_EMPTY);

$upperWords = array_filter($upperWords, function($val) {
    if(!ctype_upper($val)) {
        return false;
    }
    return true;
});
if($upperWords == false) {
    echo "<p>" . htmlspecialchars($text) . "</p>";
    die;
}
$upperWords = array_unique($upperWords);
$upperWords = array_combine(range(0, count($upperWords) - 1), $upperWords);

function manipulate_words($wordArray) {
    $producedWords = array();

    for($i = 0; $i < count($wordArray) ;$i++) {
        if(strrev($wordArray[$i]) == $wordArray[$i]) {
            $temp = "";
            foreach (str_split($wordArray[$i]) as $char) {
                $temp .= str_repeat($char, 2);
            }
            $producedWords[] = $temp;
        } else {
            $producedWords[] = strrev($wordArray[$i]);
        }
    }
    return $producedWords;
}

$reversedDoubledWrds = manipulate_words($upperWords);

for($i = 0; $i < count($upperWords) ;$i++) {
    $text = preg_replace("/(?<=^|[^A-Za-z])(" . $upperWords[$i] . ")(?=$|[^A-Za-z])/", $reversedDoubledWrds[$i], $text);
}

echo "<p>" . htmlspecialchars($text) . "</p>";